Color reproduction method, color reproduction system, color reproduction program, and color reproduction apparatus

ABSTRACT

A color reproduction method comprises: inputting a first color gamut and a second color gamut; applying, to the first color gamut, a first color correction in which color adaptation is taken into consideration on a basis of reference white in the first color gamut and the second color gamut and a second color correction for matching basic colors in the first color gamut and the second color gamut with each other; applying, to a first color gamut to which the first color correction and the second color correction are applied, a third color correction for correcting a color that is present in colors outside of the second color gamut to colors on a surface or inside of the second color gamut; and generating color conversion information for converting the first color gamut into the second color gamut.

TECHNICAL FIELD

The present invention relates to a color reproduction method, a colorreproduction system, a color reproduction program, and a colorreproduction apparatus. More specifically, the present invention relatesto a color reproduction method, a color reproduction system, a colorreproduction program, and a color reproduction apparatus capable ofreproducing a color image in which a reproduced color gamut is supposed,or a color image having unbroken gradation by using a color gamut in acolor image reproduction system or a color image apparatus at a maximum.

BACKGROUND ART

There is a problem that how a difference between color reproductions isabsorbed in a color reproduction from a color space having a certaincolor gamut to a color space having a different color gamut.

An example of a related color reproduction method is disclosed in PatentLiterature 1.

In Patent Literature 1, a method for providing a color conversion tablecreating program capable of easily adjusting clipping and compression inaccordance with a user's taste is provided. Specifically, in the colorconversion table creating program for creating a color conversion tablefor mapping a color in a first color gamut that is a color gamut of afirst color device into a second color gamut that is a color gamut of asecond color device, a computer is caused to execute the programcomprising a color gamut information read step of reading informationabout the first color gamut and information about the second colorgamut, a color conversion amount input step of inputting the amount ofcolor conversion in a color gamut, and a mapping step of conductingmapping by changing a mixing ratio of mapping by clipping to mapping bycompression in accordance with the input amount of color conversion whenmapping is conducted on the basis of the read information about thefirst color gamut and the information about the second color gamut.

CITATION LIST Patent Literature

-   [Patent Literature 1] Japanese Laid-open Patent Publication No.    2008-118335

SUMMARY OF INVENTION Technical Problem

In a method of Patent Literature 1 described in Background Art, becauseclipping is adopted to a color outside of a color gamut, gradation ofthe color in an original color space is not kept. Specifically, aplurality of colors reproduced as different colors in the color gamut ofa first color device are reproduced as one color on a surface of thecolor gamut in a second color device, and therefore an image reproducedon the second color device is not necessarily optimum. As describedabove, there is a problem that in the method of Patent Literature 1,gradation in the image normally reproduced by the first color devicecannot be normally reproduced by the second color device. In addition,there is a problem that in the second color device, about an arbitraryinput color, a hue, saturation, and a value cannot be corrected in therange of the color gamut of the second color device, and therefore it isdifficult to realize the color reproduction suiting the user's taste.

In view of the foregoing, it is an object of the present invention toprovide a color reproduction method, a color reproduction system, and acolor reproduction program in which when a color image a reproducedcolor gamut of which is supposed is reproduced in the color image systemor the color image apparatus having a color gamut different from that ofthe color image, the color gamut of the color image system or the colorimage apparatus is effectively used and the gradation of the color imageis kept.

Solution to Problem

In the present invention, a color reproduction method includes inputtinga first color gamut on an input side and a second color gamut on anoutput side; applying, to the first color gamut, a first colorcorrection in which color adaptation is taken into consideration on thebasis of reference white in the first color gamut and the second colorgamut and a second color correction for matching basic colors in thefirst color gamut and the second color gamut with each other; applying,to a first color gamut to which the first color correction and thesecond color correction are applied, a third color correction forcorrecting a color that is present in colors outside of the second colorgamut to colors on a surface or inside of the second color gamut; andgenerating color conversion information for converting the first colorgamut into the second color gamut.

In the present invention, a color reproduction system includes means forreading a first color gamut on an input side and a second color gamut onan output side; a first color correction means for performing a firstcolor correction in which color adaptation is taken into considerationon the basis of reference white in the first color gamut and the secondcolor gamut; a first color correction means for performing a secondcolor correction for matching basic colors in the first color gamut andthe second color gamut with each other; and a third color correctionmeans for performing a third color correction for correcting a colorthat is present in colors outside of the second color gamut to colors ona surface or inside of the second color gamut with respect to the firstcolor gamut to which the first color correction and the second colorcorrection are applied, wherein color conversion information forconverting the first color gamut into the second color gamut isgenerated.

In the present invention, a program for causing a computer to execute aprocedure for reading a first color gamut on an input side and a secondcolor gamut on an output side; a first color correction procedure forperforming a first color correction in which color adaptation is takeninto consideration on the basis of reference white in the first colorgamut and the second color gamut; a first color correction procedure forperforming a second color correction for matching basic colors in thefirst color gamut and the second color gamut with each other; and athird color correction procedure for performing a third color correctionfor correcting a color that is present in colors outside of the secondcolor gamut to colors on a surface or inside of the second color gamutwith respect to the first color gamut to which the first colorcorrection and the second color correction are applied, wherein colorconversion information for converting the first color gamut into thesecond color gamut is generated.

Advantageous Effect of Invention

According to the present invention, in a color image system or a colorimage apparatus having a color gamut different from the color gamut acolor image of which is supposed, a color reproduction in whichgradation is kept can be realized.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram showing a configuration according to a firstembodiment of the present invention.

FIG. 2 is a flowchart showing operations of the first embodiment.

FIG. 3 is a view showing a specific example in which a first color gamutand a second color gamut are displayed on a color space.

FIG. 4 is a view showing a concept of a color correction based on basiccolors of a second color correction means.

FIG. 5 is a view showing a specific example of the color correctionbased on the basic colors of the second color correction means.

FIG. 6 is a view showing a state in which the second color gamut isdivided by a trigonal pyramid in which measuring points are used asvertexes.

FIG. 7 is a view showing inside and outside determination results of thesecond color gamut of colors in the first color gamut.

FIG. 8 is a view showing an example of a user interface for a colorgamut correction used in a third color correction means.

FIG. 9 is a block diagram showing a configuration according to a secondembodiment of the present invention.

FIG. 10 is a flowchart showing operations of the second embodiment.

FIG. 11 is a view showing an example of the user interface for the colorcorrection used in a fourth color correction means.

FIG. 12 is a block diagram showing a configuration according to a thirdembodiment of the present invention.

FIG. 13 is a view showing a specific color correction through the userinterface according to the third embodiment of the present invention.

FIG. 14 is a block diagram showing examples of the present invention.

DESCRIPTION OF EMBODIMENTS First Embodiment

A first embodiment of the present invention will be described in detailbelow with reference to the accompanying drawings.

FIG. 1 is a block diagram showing a color reproduction system 100 of thefirst embodiment.

The color reproduction system 100 according to the first embodiment ofthe present invention inputs a first color gamut and a second colorgamut, and outputs color conversion information from the first colorgamut to the second color gamut. Further, the color reproduction system100 includes a color gamut input means 1, a color gamut display means 2,a first color correction means 3, a second color correction means 4, athird color correction means 5, and a color gamut correction interfacemeans 6.

An outline of operations of these means is as described below.

The color gamut input means 1 reads a first color gamut being a colorgamut on the input side and a second color gamut being a color gamut onthe output side.

The color gamut display means 2 displays the first color gamut and thesecond color gamut on a color space. Here, examples of the color spaceinclude a uniform color space CIELAB, HSV (H: Hue, S: Saturation, V:Value), and the like.

When reference white of the first color gamut and that of the secondcolor gamut are different from each other, the first color correctionmeans 3 applies to the first color gamut a color correction in whichcolor adaptation of human beings is taken into consideration.

The second color correction means 4 applies a color correction so that abasic color in the first color gamut to which the color correction isapplied by the first color correction means 3 is matched with acorresponding basic color in the second color gamut.

When a color positioned outside of the second color gamut is stillpresent in the first color gamut to which a color gamut conversionthrough the second color correction means 4 is applied, the third colorcorrection means 5 performs a color correction so that the color is acolor on a surface or inside of the second color gamut.

When the color correction of the third color correction means 5 isapplied, the color gamut correction interface means 6 selects a color tobe corrected from the first color gamut displayed on the color gamutdisplay means 2 and provides to a user a parameter by which the selectedcolor is corrected.

When a color of the first color gamut is corrected to a color on asurface or inside of the second color gamut, the color reproductionsystem 100 collectively outputs a series of correction results as thecolor conversion information from the first color gamut to the secondcolor gamut.

Next, the entire operations of the present embodiment will be describedin detail with reference to flowcharts of FIGS. 1 and 2.

As shown in the flowchart of FIG. 2, in the entire operations of thepresent embodiment, a read step of the color gamut (S1), a color spacedisplay step of the color gamut (S2), a color correction step in whichthe color adaptation is taken into consideration (S3), a colorcorrection step based on the basic colors (S4), and a color gamutcorrection step through the user interface (S5) are operated in order.Each step will be described.

First, in the read step of the color gamut (S1), information about thefirst color gamut as an input color space and information about thesecond color gamut as an output color space are read. Here, these colorgamuts are regions to which a correspondence relationship between devicecolors for expressing colors such as RGB or CMYK and tristimulus valuesXYZ is known. For example, the color gamut in which a transformationmatrix and gamma characteristics between the RGB and the tristimulusvalues XYZ are mutually defined like sRGB may be used, or the colorgamut in which a color reproduced by a color image device is actuallymeasured may be used.

The color gamut input means 1 operates like the above S1.

In the color space display step of the color gamut (S2), the read firstand second color gamuts are displayed on the color space. Here, a colorspace such as the tristimulus values XYZ, the uniform color spaceCIELAB, or the HSV (H: Hue, S: Saturation, V: Value) can be used as thecolor space. FIG. 3 shows an example in which the first color gamut andthe second color gamut are displayed on the uniform color space CIELAB.Here, the color gamut indicated by using a dotted line is set to beexpressed as the first color gamut, and the color gamut indicated byusing a solid line is set to be expressed as the second color gamut.

The color gamut display means 2 operates like the above S2.

In the color correction step in which the color adaptation is taken intoconsideration (S3), when the reference white in the first color gamutand the reference white in the second color gamut are different fromeach other, the color correction in which the color adaptation of humanbeings is taken into consideration is applied to the first color gamut.Suppose that the reference white of two color gamuts are different fromeach other, or even if the two reference white are the same, observationenvironments are different from each other. In this case, even if thetristimulus values XYZ are matched with each other, the tristimulusvalues XYZ may fail to be perceived as the same color to human beings.The color adaptation conversion is the above-described color correctionprocess for compensating a phenomenon about an observation of colors forhuman beings, and various methods such as von Kries, CIECAM02, andJapanese Laid-open Patent Publication No. 2000-113174 are proposed. Inthe present embodiment, the color adaptation conversions are applicable.

The first color correction means 3 operates like the above S3.

In the color correction step based on the basic colors (S4), the colorcorrection for matching the basic color in the first color gamut withthe corresponding basic color in the second color gamut is applied tothe first color gamut. FIG. 4 is a view showing a concept of the colorcorrection based on the basic colors.

In this figure, a state in which two color gamuts in which the colordevice is RGB are indicated by using an xy chromaticity diagram isshown. It is understood that coordinate positions of R, G, and B beingthe basic colors in the two color gamuts are different from each other.In the color correction based on the basic colors, because hues may bedifferent from each other, the basic colors in the first color gamut onthe input side are reproduced by the basic colors in the second colorgamut on the output side. Further, as the basic colors are moreapproximated to an achromatic color, the basic colors in the first colorgamut on the input side are reproduced by colors more approximated to anoriginal color in the first color gamut on the input side. The colorcorrection based on this basic color has the advantage of being able toeffectively use the color gamut on the output side.

Calculation procedures of the color correction based on the basic colorswill be described below. Here, a color device of the first color gamutwill be described as RGB.

First, R (255, 0, 0), G (0, 255, 0), B (0, 0, 255), C (0, 255, 255), M(255, 0, 255), and Y (255, 255, 0) in the first color gamut are set tothe basic colors. Further, the first color correction, namely, the colorcorrection in which the color adaptation of human beings is taken intoconsideration is applied, and then the tristimulus values XYZ of eachbasic color are calculated and further L*a*b* of the uniform color spaceCIELAB is calculated.

Next, on the basis of the tristimulus values XYZ corresponding to sixbasic colors, namely, R (255, 0, 0), G (0, 255, 0), B (0, 0, 255), C (0,255, 255), M (255, 0, 255), and Y (255, 255, 0) in the second colorgamut, the L*a*b* is calculated.

A correction vector to the basic color in the first color gamut on theinput side to which the first color correction is applied and acorrection vector to the corresponding basic color in the second colorgamut are calculated in the uniform color space CIELAB. FIG. 5 shows thecolor correction to a space extending between Y and G in the first colorgamut by using a two-dimensional plane a*b*. The Y and G are Y and G inthe first color gamut on the input side to which the first colorcorrection is applied, and Yp and Gp are Y and G in the second colorgamut. A correction vector V1 at the time when mapping is conducted fromY (L_(y), a_(y), b_(y)) to Yp (L_(py), a_(py), b_(py)) is represented bythe following equation.

Correction vector=(L _(py) ,a _(py) ,b _(py))−(L _(y) ,a _(y) ,b_(y))  (1)

In the similar fashion, the correction vectors are calculated also aboutthe residual basic colors (R, G, B, C, M).

Next, a method for applying the second color correction to colors exceptthe basic colors will be described.

In the second color correction with respect to the colors except thebasic colors, on the basis of characteristics in which as a color ismore approximated to an achromatic color, a color perception of humanbeings becomes sharper, a color correction in which a color to becorrected is far away from a white color as shown in FIG. 4, namely, asthe saturation becomes higher, corrected intensity is more intensifiedis applied.

A correction vector Vx that is allowed to act on a point X in the Labspace in the first color gamut on the input side to which the firstcolor correction is applied is calculated. An example of the secondcolor correction will be described with reference to the example of FIG.5. In this case, the point X is present in the color space extendingbetween the Y and the G. In this case, the correction vector Vx that isallowed to act on the X is calculated by using the correction vectors V1and V2 in which the Y and the G are calculated. First, a hue H andsaturation C of Y, G, and the point X in the first color gamut on theinput side to which the first color correction is applied arecalculated, respectively. A hue angle between the Y and the G is set todH, and a hue angle between the Y and the X is set to dH1. SaturationC_(X) of the X is calculated, and at the same time, Y, G, and X areprojected onto the ab plane. Further, an intersection point of a segmentGY in which G is connected to Y on the ab plane and a straight linepassing through the X and the L axis on the ab plane is calculated, andthe saturation C of the intersection point is calculated. Next, acorrection vector Vh that contributes to a hue component is calculated.

Vh=(1−dH1/dH)·V1+(dH1/dH)·V2  (2)

Further, a contribution of a saturation component is reflected on thecorrection vector Vh, and the correction vector Vx that acts on thepoint X is calculated.

Vx=Cx/C·Vh  (3)

A result in which the correction vector Vx is applied to the point X inthe uniform color space CIELAB is a result of the second colorcorrection with respect to the colors except the basic colors.

Further, color device values RGB in the second color gamut correspondingto the L*a*b* in the uniform color space CIELAB to which the secondcolor correction is applied are calculated. Now, in the case where acorrespondence relationship between the tristimulus values XYZ and thecolor device values in the second color gamut is defined as a standardcolor space such as sRGB or AdobeRGB, the color device values RGB can beeasily calculated in accordance with the specified equation. On theother hand, in the case where the correspondence relationship betweenthe tristimulus values XYZ and the color device values is not defined byusing the equation in the second color gamut, the color device valuesare calculated on the basis of the correspondence relationship betweenthe tristimulus values XYZ and the color device values RGB obtained bythe measurement. A method for calculating the color device values ofthis case will be described.

The correspondence relationship between the tristimulus values XYZ andthe color device values in the second color gamut is supposed to beobtained by the measurement. The L*a*b* is calculated on the basis ofthe tristimulus values XYZ being the measuring points and thecorrespondence relationship between the L*a*b* and the color devicevalues is obtained. Then, a trigonal pyramid in which adjacent measuringpoints are used as vertexes is created. Thereby, the second color gamutin the uniform color space CIELAB is tightly filled with the trigonalpyramids in which the measuring points are used as the vertexes. Asshown in FIG. 6, the second color gamut in the uniform color spaceCIELAB is supposed to be divided by the trigonal pyramid in which theadjacent measuring points are used as the vertexes. The point Y in theuniform color space CIELAB is considered. In the case where the point Yis present in the second color gamut, the point Y is necessarily presentinside of a piece of the trigonal pyramid in which the measuring pointsare used as the vertexes. As shown in FIG. 6, in the case where thepoint Y is present in the trigonal pyramid in which A0, A1, A2, and A3are used as the vertexes, all of the following condition equations (4),(5), and (6) are satisfied.

{right arrow over (X)}−

=a(

)+b(

)+b(

)  (4)

a,b,c≧0  (5)

a+b+c≦1  (6)

Herein, {right arrow over (X)} and

(i=0 to 3) denote position vectors from an origin in the CIELAB colorspace.

About the point Y, the trigonal pyramid that satisfies the conditionequations (4) to (6) may be searched for from among all the trigonalpyramids constituting the second color gamut. Further, when the point Yis positioned on a surface or a vertex of the trigonal pyramid, aplurality of the trigonal pyramids satisfy the condition equations (4)to (6). In that case, any one of the trigonal pyramids may be selected.

Next, the color device values C in the second color gamut correspondingto the point Y are calculated. Now, when the color device valuescorresponding to the vertexes A0, A1, A2, and A3 of the trigonal pyramidincluding the point Y are set to C0, C1, C2, and C3, the color devicevalue C is represented by the following equation.

C=(1−a−b−c)C0+a·C1+b·C2+c·C3  (7)

Here, coefficients a, b and c are the same coefficients as those in theequation 4.

The second color correction means 4 operates like the above S4.

Next, the color gamut correction step through the user interface (S5)will be described. In the case where in the first color gamut to whichthe color correction step in which the color adaptation is taken intoconsideration (S3) and the color correction step based on the basiccolors (S4) are applied, a color is still present outside of the secondcolor gamut, a color of the first color gamut is further required tocorrected to a color on a surface or inside of the second color gamut.Here, by the use of the first and second color gamuts displayed on thecolor space display step of the color gamut (S2) and the user interfacefor the color gamut correction, such a color is corrected.

Now, from the first color gamut to which the color correction step inwhich the color adaptation is taken into consideration (S3) and thecolor correction step based on the basic colors (S4) displayed on thecolor space display step of the color gamut (S2) are applied, a coloroutside of the second color gamut is selected. Here, about theinner/outer determination of the second color gamut, whether thetrigonal pyramids constituting the second color gamut that satisfy thecondition equations (4) to (6) are present can be easily determined. Asshown in FIG. 7, in the color space display step of the color gamut(S2), by changing a color displaying the point or a size of the point,colors constituting the first color gamut that are determined to beoutside of the second color gamut can be displayed so that the usereasily selects colors outside of the color gamut. Further, FIG. 7 is anexample in which colors constituting the first color gamut that aredetermined to be inside of the second color gamut and colorsconstituting the first color gamut that are determined to be outside ofthe second color gamut are displayed by changing the size of the pointso that the user easily selects a color outside of the color gamut.

About the color correction to the color outside of the second colorgamut selected by the user, the user interface for determiningparameters in the color gamut correction as shown in FIG. 8 is proposedand the parameters are determined. In FIG. 8, an LCH calculated on thebasis of (L*, a*, b*) of the selected color is displayed. Here, Ldenotes the value and is L*. C denotes the saturation and H denotes thehue. C and H are calculated by the following equations.

C=√{square root over (a*² +b* ²)}  (8)

H=arctan(b*/a*)  (9)

Here, the hue H is indicated by using radian, and further when the hue His indicated by an angle H′, the hue H is calculated below.

H′=180−H/π  (10)

Here, in the case of H′<0

H′=180−H/π+360  (11)

The correction amount to each component of the LCH calculated by theabove (8) to (11) of the selected color is specified by the userinterface shown in FIG. 8. In the case of the interface of FIG. 8, eachcomponent of the selected LCH is corrected while the color is controlledby a slide bar so that the color is a color on a surface or inside ofthe second color gamut. When a color to be corrected is a color on asurface or inside of the second color gamut during the correction, acolor or a size indicating the point changes in conjunction with eachother as shown in FIG. 7.

Here, the correction amount to the selected color or also to theadjacent colors is applied in the form of gradually weakening thecorrection amount and the correction is geared. Thereby, a reversalphenomenon of the color can be avoided. Further, a plurality of colorsthat are present around a color desired to be corrected are selected andcorrected at the same time, and thereby an operating efficiency in thisstep is improved.

When all the colors in the first color gamut are corrected to a color ona surface or inside of the second color gamut, the color gamutcorrection step through the user interface (S5) is ended.

The third color correction means 5 operates like the above S5, and thecolor gamut correction interface means 6 is realized, for example, bythe user interface shown in FIG. 8.

In the color correction through the user interface, to the colorsoutside of the color gamut on the output side, clipping is not appliedand a reversal of the color is not generated. Therefore, the colorreproduction in which gradation is kept can be realized. Further, thecolor reproduction suiting the user's taste can be realized on the basisof the color correction through the user.

Through the above steps, color conversion information from the firstcolor gamut to the second color gamut is generated. Here, the colorconversion information from the first color gamut to the second colorgamut can be output, for example, as a color conversion table in whichthe correspondence relationship between the color device values in theinput color space and the color device values in the output color spaceis recorded.

Next, advantageous effects of the present embodiment will be described.

In the present embodiment, under conditions in which the color gamut onthe input side and the color gamut on the output side are different fromeach other, by the configuration of the color correction step based onthe basic colors and the color gamut correction step through the userinterface, the color gamut on the output side can be effectively usedand the color reproduction in which the gradation is kept can berealized. Further, the color reproduction suiting the user's taste canbe realized.

In particular, in the color image system or the color image apparatushaving the color gamut different from that supposed to be a color image,the color reproduction in which the gradation is kept can be realized.The reason is that the color gamut of the color image system or thecolor image apparatus is effectively used, and in particular theclipping is not applied to the colors outside of the color gamut in aprocess of the color reproduction.

Further, in the color image system or the color image apparatus havingthe color gamut different from that supposed in a color image, the colorreproduction suiting the user's taste can be realized. The reason isthat about an arbitrary color, the hue, the saturation, and the valuecan be corrected in the range of the color gamut of the color imagesystem or the color image apparatus.

Second Embodiment

A second embodiment of the present invention will be described in detailbelow with reference to the accompanying drawings.

With reference to FIG. 9, a color reproduction system 200 of a preferredembodiment for embodying the second embodiment of the present inventionhas a configuration in which a fourth color correction means 7 and acolor correction interface means 8 are added to the color reproductionsystem 100.

Here, the newly-added fourth color correction means 7 and colorcorrection interface means 8 will be described.

The fourth color correction means 7 further provides the colorcorrection suiting the user's taste to the color corrected so as to bereproduced in the second color gamut by applying the first to thirdcolor corrections to the first color gamut.

When the color correction in the fourth color correction means 7 isapplied, the color correction interface means 8 selects a color to becorrected and provides to the user a parameter for correcting theselected color.

Next, the entire operations of the present embodiment will be describedin detail with reference to flowcharts of FIGS. 9 and 10.

As shown in the flowchart of FIG. 10, in the entire operations of thepresent embodiment, a read step of the color gamut (S1), a color spacedisplay step of the color gamut (S2), a color correct step in which thecolor adaptation is taken into consideration (S3), a color correctionstep based on the basic colors (S4), a color gamut correction stepthrough the user interface (S5), and a specific color correction throughthe user interface (S6) are operated in order. Here, the newly-addedspecific color correction through the user interface (S6) will bedescribed.

In the specific color correction through the user interface (S6), to thecolor corrected so as to be reproduced in the second color gamut byapplying the first to third color corrections to the first color gamut,the color correction is further applied so as to suit the user's taste.

FIG. 11 shows an example of the user interface for the color correctionto be used in S6. On the left side of FIG. 11, the first and secondcolor gamuts displayed on the color gamut display means 2 are shown.Further, the first to third color corrections are applied to the firstcolor gamut, and thereby an arbitrary color in the first color gamutindicates a state capable of being reproduced in the second color gamut.Now, the colors constituting the first color gamut that are displayed onthe color gamut display means 2 are selected by a mouse operation of thecomputer. From the L*a*b* values of the selected colors, the hue, thesaturation, and the value of the colors are calculated and plotted on agraph indicated by the hue-saturation on the interface for colorcorrection on the right side of FIG. 11. In addition, the value of thegraph indicated by the hue-saturation is indicated by the same value asthat of the selected color. The plotted point is moved on the graphindicated by the hue-saturation, and thereby the hue and the saturationof the selected color can be corrected. Further, by changing anadjustment bar of the value, the value of the selected color can becorrected. A color before the correction and that after the correctionof the selected color can be confirmed on the interface for colorcorrection. Correction results in the interface for color correction arereflected on the first color gamut. Here, when the correction resultsare reflected on the first color gamut, only the selected color may bereflected or also colors around the selected color may be reflected. Inthe case where also the colors around the selected color are reflected,the correction amount is adjusted on the basis of a color difference, ahue difference, a saturation difference, and a value difference betweenthe colors around the selected color and the selected color, and therebythe color reproduction with no uncomfortable feeling can be realized.

Further, results of the specific color correction through the userinterface (S6) are reflected on the color conversion information fromthe first color gamut to the second color gamut.

The fourth color correction means 7 operates like the above S6, and thecolor correction interface means 8 provides the interface for the colorcorrection performed by the fourth color correction means 7 as shown inFIG. 11.

Advantageous effects of the present embodiment will be described.

In the present embodiment, by the configuration of the specific colorcorrection step through the user interface, when a color in the colorgamut on the input side is reproduced by the color gamut on the outputside, the color reproduction more suiting the user's taste can berealized.

Third Embodiment

A third embodiment of the present invention will be described in detailbelow with reference to the accompanying drawings.

With reference to FIG. 12, a color reproduction system 300 according tothe third embodiment of the present invention has a configuration inwhich an evaluation image display means 9 is added to the colorreproduction system 200.

When the color correction is performed so as to suit the user's taste,the evaluation image display means 9 can select a color to be correctedfrom the proposed evaluation image and confirm advantageous effects ofthe color correction as an image, and provides a color correctionfunction having higher user-friendliness.

About the basic operations, as shown in the flowchart of FIG. 10, amethod for selecting a color to be corrected is different only in thespecific color correction through the user interface (S6), and thereforethe newly-added evaluation image display means 9 will be hereindescribed.

As shown in FIG. 13, the evaluation image display means 9 proposes, tothe color image apparatus having the second color gamut, the evaluationimage with the color on which the color conversion information from thefirst color gamut to the second color gamut is reflected. Here, variousimages such as a person image, a scenery image, and a CG image aresupposed to be able to be prepared and selected as the evaluation image.The user is allowed to select a color to be corrected from the proposedevaluation images. The color correction to the selected color is asdescribed in the above-described specific color correction through theuser interface (S6).

Results of the specific color correction through the user interface (S6)are reflected on the color conversion information from the first colorgamut to the second color gamut to be thereby proposed.

In the advantageous effects of the present embodiment, through theabove-described configuration, when the color correction is performed soas to suit the user's taste, the color to be corrected can be selectedfrom the proposed evaluation image and the advantageous effects of thecolor correction can be confirmed as an image. As a result, the colorcorrection having higher user-friendliness can be realized.

First Example

Next, operations of preferred embodiments for embodying the presentinvention will be described with reference to specific examples.

The color reproduction systems 100 to 300 according to theabove-described first to third embodiments can be realized also as aprogram to be executed on the computer. Further, as shown in FIG. 14,the color reproduction systems 100 to 300 can be realized also as acolor reproduction apparatus 400.

The color reproduction apparatus 400 inputs the first color gamut andthe second color gamut, and outputs the color conversion informationfrom the first color gamut to the second color gamut. The colorreproduction apparatus 400 includes the color gamut input means 1, thecolor gamut display means 2, the first color correction means 3, thesecond color correction means 4, the third color correction means 5, thecolor gamut correction interface means 6, and a color gamut storagememory 10.

Each means of the color gamut input means 1, the color gamut displaymeans 2, the first color correction means 3, the second color correctionmeans 4, the third color correction means 5, and the color gamutcorrection interface means 6 carries out the same operations as those ofthe means described in the color reproduction system 100. The colorgamut storage memory 10 is a memory that stores the first color gamutand the second color gamut by using the color gamut input means 1.

On the first color gamut stored in the color gamut storage memory 10,correction results of the first color correction means 3, the secondcolor correction means 4, and the third color correction means 5 arereflected in each case.

As described above, the present invention is described with reference topreferred embodiments and examples. Further, the present invention isnot necessarily limited to the above embodiments and examples, but canbe variously verified and performed in a range of technical idea.

Further, part or the whole of the above embodiments can be describedlike the following supplementary notes; however, is not limited thereto.

(Supplementary note 1) A color reproduction method including:

inputting a first color gamut on an input side and a second color gamuton an output side;

applying, to the first color gamut, a first color correction in whichcolor adaptation is taken into consideration on the basis of referencewhite in the first color gamut and the second color gamut and a secondcolor correction for matching basic colors in the first color gamut andthe second color gamut with each other;

applying, to a first color gamut to which the first color correction andthe second color correction are applied, a third color correction forcorrecting a color that is present in colors outside of the second colorgamut to colors on a surface or inside of the second color gamut; and

generating color conversion information for converting the first colorgamut into the second color gamut.

(Supplementary note 2) The color reproduction method described in thesupplementary note 1, wherein with respect to colors except basiccolors, the second color correction is a color correction in which assaturation is higher, corrected intensity is more intensified.

(Supplementary note 3) The color reproduction method described in thesupplementary note 1 or 2, wherein in the second color correction, tothe colors except the basic colors, a color correction is performed onthe basis of color correction information about two basic colorsinterleaving the color except the basic colors.

(Supplementary note 4) The color reproduction method described in anyone of the supplementary notes 1 to 3, wherein in the third colorcorrection, the second color gamut and a color gamut in which the firstcolor correction and the second color correction are applied to thefirst color gamut are displayed on a color space, and a color that ispresent in the colors outside of the second color gamut is selected by auser interface, and is corrected to colors on a surface or inside of thesecond color gamut.

(Supplementary note 5) The color reproduction method described in anyone of the supplementary notes 1 to 4, wherein from colors constitutingthe first color gamut that constitute the color conversion information,a fourth color correction for changing a parameter of the color selectedby the user interface is performed.

(Supplementary note 6) The color reproduction method described in thesupplementary note 5, wherein in the fourth color correction, a color tobe corrected is selected from colors of an evaluation image proposed onan image apparatus having the second color gamut.

(Supplementary note 7) A color reproduction system including:

a means configured to read a first color gamut on an input side and asecond color gamut on an output side;

a first color correction means configured to perform a first colorcorrection in which color adaptation is taken into consideration on thebasis of reference white in the first color gamut and the second colorgamut;

a first color correction means configured to perform a second colorcorrection for matching basic colors in the first color gamut and thesecond color gamut with each other; and

a third color correction means configured to perform a third colorcorrection for correcting a color that is present in colors outside ofthe second color gamut to colors on a surface or inside of the secondcolor gamut with respect to the first color gamut to which the firstcolor correction and the second color correction are applied, wherein

color conversion information for converting the first color gamut intothe second color gamut is generated.

(Supplementary note 8) The color reproduction system described in thesupplementary note 7, wherein with respect to the colors except thebasic colors, the second color correction means performs a colorcorrection in which as saturation is higher, corrected intensity is moreintensified.

(Supplementary note 9) The color reproduction system described in thesupplementary note 7 or 8, wherein with respect to the colors except thebasic colors, the second color correction means performs a colorcorrection on the basis of color correction information about two basiccolors interleaving the color except the basic colors.

(Supplementary note 10) The color reproduction system described in anyone of the supplementary notes 7 to 9, wherein the third colorcorrection means displays, on a color space, the second color gamut anda color gamut in which the first color correction and the second colorcorrection are applied to the first color gamut, selects a color that ispresent in the colors outside of the second color gamut by a userinterface, and corrects the above color to colors on a surface or insideof the second color gamut.

(Supplementary note 11) The color reproduction system described in anyone of the supplementary notes 7 to 10, further including a fourth colorcorrection means for changing a parameter of the color selected by theuser interface from colors constituting the first color gamut thatconstitute the color conversion information.

(Supplementary note 12) The color reproduction system described in thesupplementary note 11, wherein the fourth color correction means selectsa color to be corrected from colors of an evaluation image proposed onan image apparatus having the second color gamut.

(Supplementary note 13) A program for causing a computer to execute:

a procedure for reading a first color gamut on an input side and asecond color gamut on an output side;

a first color correction procedure for performing a first colorcorrection in which color adaptation is taken into consideration on thebasis of reference white in the first color gamut and the second colorgamut;

a first color correction procedure for performing a second colorcorrection for matching basic colors in the first color gamut and thesecond color gamut with each other; and

a third color correction procedure for performing a third colorcorrection for correcting a color that is present in colors outside ofthe second color gamut to colors on a surface or inside of the secondcolor gamut with respect to the first color gamut to which the firstcolor correction and the second color correction are applied, wherein

color conversion information for converting the first color gamut intothe second color gamut is generated.

(Supplementary note 14) The program described in the supplementary note13, wherein with respect to the colors except the basic colors, thesecond color correction procedure is a procedure for performing a colorcorrection in which as saturation is higher, corrected intensity is moreintensified.

(Supplementary note 15) The program described in the supplementary note13 or 14, wherein with respect to the colors except the basic colors,the second color correction procedure is a procedure for performing acolor correction on the basis of color correction information about twobasic colors interleaving the color except the basic colors.

(Supplementary note 16) The program described in any one of thesupplementary notes 13 to 15, wherein the third color correctionprocedure is a procedure for displaying, on a color space, the secondcolor gamut and a color gamut in which the first color correction andthe second color correction are applied to the first color gamut,selecting a color that is present in the colors outside of the secondcolor gamut by a user interface, and correcting the above color tocolors on a surface or inside of the second color gamut.

(Supplementary note 17) The program described in any one of thesupplementary notes 13 to 16, further including a fourth colorcorrection procedure for changing a parameter of the color selected bythe user interface from colors constituting the first color gamut thatconstitute the color conversion information.

(Supplementary note 18) The program described in the supplementary note17, wherein the fourth color correction procedure is a procedure forselecting a color to be corrected from colors of an evaluation imageproposed on an image apparatus having the second color gamut.

(Supplementary note 20) A color reproduction method including:

inputting a first color gamut on an input side and a second color gamuton an output side;

generating a first color correction in which color adaptation is takeninto consideration on the basis of reference white in the first colorgamut and the second color gamut and a second color correction forconverting a basic color in the first color gamut into a basic color inthe second color gamut;

applying the first color correction and the second color correction tothe first color gamut to generate a correction color gamut, andgenerating the third color correction for performing the colorcorrection to colors constituting the correction color gamut that arepresent outside of the second color gamut; and

generating conversion information for converting the first color gamutinto the second color gamut.

(Supplementary note 21) A color reproduction method including:

inputting a first color gamut on an input side and a second color gamuton an output side in which a correspondence relationship between colordevice values and tristimulus values is known;

generating a first color correction for converting a basic color in thefirst color gamut into a desired color in the second color gamut;

generating a second color correction for correcting the colors exceptthe basic colors in the first color gamut;

applying the first color correction and the second color correction tothe first color gamut and generating a correction color gamut;

applying a third color correction along with a user interface forperforming a color correction in a uniform color space to an arbitrarycolor in the correction color gamut, and

generating color conversion information about a color in the secondcolor gamut corresponding to an arbitrary color in the first colorgamut.

(Supplementary note 22) The color reproduction method described in thesupplementary note 20 or 21, wherein in the first color correction, thesame basic color in the first color gamut or colors, color device valuesof which are matched with each other are selected as the desired colorin the second color gamut.

(Supplementary note 23) The color reproduction method described in anyone of the supplementary notes 20 to 22, wherein in the second colorcorrection, color correction information about a color to be correctedis generated on the basis of the color correction information obtainedby the first color correction with respect to two basic colorsinterleaving the color to be corrected.

(Supplementary note 24) The color reproduction method described in anyone of the supplementary notes 20 to 23, wherein in the user interfaceof the third color correction, an evaluation image is proposed to theuser on a color image apparatus having the second color gamut, and theuser can confirm advantageous effects of the first color correction, thesecond color correction, and the third color correction by theevaluation image.

(Supplementary note 25) The color reproduction method described in thesupplementary note 24, wherein in the user interface of the third colorcorrection, a color to be corrected by the third color correction isselected from colors of the evaluation image proposed on a color imageapparatus having the second color gamut.

This application is based upon and claims the benefit of priority of theprior Japanese Patent Application No. 2012-052107, filed on Mar. 8,2012, the entire contents of which are incorporated herein by reference.

INDUSTRIAL APPLICABILITY

The present invention is applicable to the color reproduction system,the color reproduction program, and the color reproduction apparatusbetween the color image reproduction systems or the color imageapparatus that are different in the color gamut. Further, the presentinvention is applicable also to a function of creating a colorconversion table between the color image reproduction systems or thecolor image apparatus that are different in the color gamut.

REFERENCE SIGNS LIST

-   1 Color gamut input means-   2 Color gamut display means-   3 First color correction means-   4 Second color correction means-   5 Third color correction means-   6 Color gamut correction interface means-   7 Fourth color correction means-   8 Color correction interface means-   9 Evaluation image display means-   10 Color gamut storage memory-   100 Color reproduction system-   200 Color reproduction system-   300 Color reproduction system-   400 Color reproduction apparatus

1. A color reproduction method comprising: inputting a first color gamut on an input side and a second color gamut on an output side; applying, to the first color gamut, a first color correction in which color adaptation is taken into consideration on a basis of reference white in the first color gamut and the second color gamut and a second color correction for matching basic colors in the first color gamut and the second color gamut with each other; applying, to a first color gamut to which the first color correction and the second color correction are applied, a third color correction for correcting a color that is present in colors outside of the second color gamut to colors on a surface or inside of the second color gamut; and generating color conversion information for converting the first color gamut into the second color gamut.
 2. The color reproduction method according to claim 1, wherein with respect to colors except basic colors, the second color correction is a color correction in which as saturation is higher, corrected intensity is more intensified.
 3. The color reproduction method according to claim 1, wherein in the second color correction, with respect to the colors except the basic colors, a color correction is performed on a basis of color correction information about two basic colors interleaving the color except the basic colors.
 4. The color reproduction method according to claim 1, wherein in the third color correction, the second color gamut and a color gamut in which the first color correction and the second color correction are applied to the first color gamut are displayed on a color space, and a color that is present in the colors outside of the second color gamut is selected by a user interface, and is corrected to colors on a surface or inside of the second color gamut.
 5. The color reproduction method according to claim 1, wherein from colors constituting the first color gamut that constitute the color conversion information, a fourth color correction for changing a parameter of the color selected by the user interface is performed.
 6. The color reproduction method according to claim 5, wherein in the fourth color correction, a color to be corrected is selected from colors of an evaluation image proposed on an image apparatus having the second color gamut.
 7. A color reproduction system comprising: a unit configured to read a first color gamut on an input side and a second color gamut on an output side; a first color correction unit configured to perform a first color correction in which color adaptation is taken into consideration on a basis of reference white in the first color gamut and the second color gamut; a second color correction unit configured to perform a second color correction for matching basic colors in the first color gamut and the second color gamut with each other; and a third color correction unit configured to perform a third color correction for correcting a color that is present in colors outside of the second color gamut to colors on a surface or inside of the second color gamut with respect to the first color gamut to which the first color correction and the second color correction are applied, wherein color conversion information for converting the first color gamut into the second color gamut is generated.
 8. The color reproduction system according to claim 7, wherein with respect to colors except basic colors, the second color correction unit performs a color correction in which as saturation is higher, corrected intensity is more intensified.
 9. The color reproduction system according to claim 7, wherein with respect to the colors except the basic colors, the second color correction unit performs a color correction on a basis of color correction information about two basic colors interleaving the color except the basic colors.
 10. A non-transitory computer readable storage medium storing a program for causing a computer to execute: a procedure for reading a first color gamut on an input side and a second color gamut on an output side; a first color correction procedure for performing a first color correction in which color adaptation is taken into consideration on a basis of reference white in the first color gamut and the second color gamut; a second color correction procedure for performing a second color correction for matching basic colors in the first color gamut and the second color gamut with each other; and a third color correction procedure for performing a third color correction for correcting a color that is present in colors outside of the second color gamut to colors on a surface or inside of the second color gamut with respect to the first color gamut to which the first color correction and the second color correction are applied, wherein color conversion information for converting the first color gamut into the second color gamut is generated.
 11. The color reproduction system according to claim 7, wherein the third color correction unit displays, on a color space, the second color gamut and a color gamut in which the first color correction and the second color correction are applied to the first color gamut, selects a color that is present in the colors outside of the second color gamut by a user interface, and corrects the above color to colors on a surface or inside of the second color gamut.
 12. The color reproduction system according to claim 7, further including a fourth color correction unit for changing a parameter of the color selected by the user interface from colors constituting the first color gamut that constitute the color conversion information.
 13. The color reproduction system according to claim 12, wherein the fourth color correction unit selects a color to be corrected from colors of an evaluation image proposed on an image apparatus having the second color gamut.
 14. The non-transitory computer readable storage medium storing a program according to claim 10, wherein with respect to the colors except the basic colors, the second color correction procedure is a procedure for performing a color correction in which as saturation is higher, corrected intensity is more intensified.
 15. The non-transitory computer readable storage medium storing a program according to claim 10, wherein with respect to the colors except the basic colors, the second color correction procedure is a procedure for performing a color correction on the basis of color correction information about two basic colors interleaving the color except the basic colors.
 16. The non-transitory computer readable storage medium storing a program according to claim 10, wherein the third color correction procedure is a procedure for displaying, on a color space, the second color gamut and a color gamut in which the first color correction and the second color correction are applied to the first color gamut, selecting a color that is present in the colors outside of the second color gamut by a user interface, and correcting the above color to colors on a surface or inside of the second color gamut.
 17. The non-transitory computer readable storage medium storing a program according to claim 10, further including a fourth color correction procedure for changing a parameter of the color selected by the user interface from colors constituting the first color gamut that constitute the color conversion information.
 18. The non-transitory computer readable storage medium storing a program according to claim 17, wherein the fourth color correction procedure is a procedure for selecting a color to be corrected from colors of an evaluation image proposed on an image apparatus having the second color gamut. 